This invention relates to broadcasting, and more specifically to a broadcasting system that allows a listen to receive, on demand, selected information from a receiver. Radio and television (TV) receivers are the most widely available entertainment devices in the world. Almost every car has a radio receiver. Radio receivers may also be found in offices, restaurants, etc. Almost every home in U.S. has a TV.
A conventional receiver contains a tuner that can be tuned to broadcast stations, each of them transmits signals at a predetermined radio frequency. In order to attract listeners, many broadcast stations concentrate on predetermined types of program materials. For example, some radio stations spend 80% of broadcast time on news while other stations spend 90% of broadcast time on music. Thus, music lovers would tune to a xe2x80x9cmusicxe2x80x9d radio station and news lovers would tune to a xe2x80x9cnewsxe2x80x9d station. Similarly, TV stations broadcast movies, sports, news, etc. at pre-scheduled times to match the viewing habit of most viewers. However, the interest of listeners/viewers may change briefly during the day. For example, a music lover may be interested in stock reports (e.g., Dow Jones average) in late afternoon (after the close of the stock exchanges) because he/she owns stocks. Many music stations do not announce stock reports. Thus, the music lover has to switch to a news station because many news stations announce stock reports at more frequent intervals (e.g., once every fifteen minutes). It is unlikely that the switch is made at the exact time when a stock report is announced. Thus, the music lover would have to listen to other news (which may be irrelevant to him/her) for a few minutes. Afterwards, the music lover has to switch back to the original music station. Similarly, almost all TV stations broadcast stock reports only during news programs. Thus, the viewer has to turn to other media (e.g., radios) to obtain the reports. This is frustrating for listener/viewers. It is also undesirable to the broadcast stations because they would like to keep their listeners tuned in all the time.
The present invention relates to a broadcast system that can provide, on demand, useful information to users. A broadcast station transmits radio frequency signals containing on-demand, main program, and (optional) index materials to a plurality of receivers. The receivers contain means for separating the on-demand (and also the index) materials from the main program material. The receivers contain a signal switch for selecting one of the materials. A user can decide to listen to any of these materials by pressing a button. The receivers contain control logic that can direct the signal switch to select the desired material. After the on-demand material is played, the signal switch automatically switches back to the main program material.